Procedures and devices to monitor friction bearings, especially in a reciprocating piston engine, like a combustion engine, are known from EP-B-0 141 348. On the basis of the monitoring of the main bearing of a crankshaft of a combustion engine a procedure and a device are described for monitoring the lubrication at the contact point between two parts made of different, electrically conducting materials moving relative to each other and insulated form each other by a lubrication film. The two parts lie in an electrical current with a voltage source and an external connection and which flows through the lubrication location itself. The circuit resistance which reduces with the tearing off of the lubricating film, on the one hand, and the thermoelectric voltage, on the other hand, which serves as a galvanic voltage source and appears with the tearing off of the lubricating film at the contact location because of frictional heat, are used in order to produce a current flow, which acts as a control or alarm signal across the external electrical connection of the electrical circuit at the appearance of a large area of metallic touching of the two friction bearing parts caused by a lack of lubrication and thus signals heat damage. The connection of the electric circuit is constructed as a resistance which is electrically adapted to the large area contact location. The voltage drop appearing at the resistance of the external connection is measured and used to initiate a control signal. The control signal serves, for example, to stop the combustion engine or activate an alarm device. It is useful to so design the procedure and device, that in the event of a voltage spike appearing for a short time, the control signal activation is suppressed until a previously determined time frequency of the voltage peaks and/or an increasing tendency of the amplitude occurs. No information about a suitable method of further operating the combustion engine can be found in the document.
EP 1 171 695 contains a further development of the previously described monitoring, in that the damage location can be localized. Here, too, there is no information about a continued operation of the combustion motor in the event of damage.